849 
FXUS63 KBIS 060318
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1018 PM CDT Tue Oct 5 2021

.UPDATE...
Issued at 1016 PM CDT Tue Oct 5 2021

Southerly winds continue to blow over southern/eastern portions of
the area, keeping temperatures quite mild. With that said, when
the wind diminishes temperatures will have the potential to
quickly drop, so decided to leave the low temperature forecast
alone. Otherwise, no other concerns at this time.

UPDATE Issued at 717 PM CDT Tue Oct 5 2021

Winds have diminished and humidity values have risen over 
northwest North Dakota, so the Red Flag Warning for today has been
allowed to expire. The Red Flag Warning for Wednesday for western
and much of central North Dakota remains in effect.

For the forecast update, only change needed was to increase cloud
cover a bit as some high clouds pass through.

&&

.SHORT TERM...(This evening through Wednesday)
Issued at 232 PM CDT Tue Oct 5 2021

Fire weather issues highlight the short term forecast period. 

A Red Flag Warning remains in effect through early this evening.
Currently humidities are down to around and below 10 percent
across pretty much across western North Dakota. Winds are
currently strongest in central ND but just below Wind Advisory
criteria. Within the RFW, winds the past hour have jumped to 
around 20 mph with the Williston Airport reporting 21 MPH at 3 PM 
with gusts to 30 mph. Farther south, there have been some gusts 
over 20 but sustained winds are generally 15 mph or less. 

Once winds diminish this evening, expect critical fire weather
conditions to abate pretty quickly. The rest of the night is also
expected to be quiet weather wise with dry conditions and
overnight lows generally in the mid 40s to mid 50s.

On Wednesday we are expecting another breezy to windy day across 
western and central North Dakota. We utilized the previous 
forecast highs. They were generally just a bit higher than the 
NBM guidance, yet lower than the NBM 90th percentile forecast 
highs. Typically the 90th percentile grids have been pretty good, 
or even too low, but looking at 850 mb temperatures, they drop 
pretty significantly tomorrow (2-4 degrees C) over all bu the far 
west as the main bubble of warm air pushes north into Canada and 
surface winds turn a little east of south. Winds still look to be 
strong on Wednesday with sustained winds generally in the 20-30 
mph range in the afternoon. There is a pretty substantial 
inversion at the top of the mixed layer with winds above this 
lighter. There were some mid 30 knot winds in a couple of areas, 
so some gusts to 40 mph may be possible in those locations, but 
generally expect gusts in the 30-35 mph range. The lowest 
humidities will once again be in the west, but lower than today 
(around 15 percent) and humidities in the central should drop to 
around 20-25 percent. There is some uncertainty in whether a Red 
Flag Warning is needed over eastern portions of the Fire Weather 
Watch, but given the stronger winds, and fuels available, will 
lean on the cautious side and include all counties that were in 
the FWW, in a RFW. We have already sent out the upgraded product. 
Again, temperatures will be a little cooler than today, but still 
unseasonably mild for early October. 

.LONG TERM...(Wednesday night through Tuesday)
Issued at 232 PM CDT Tue Oct 5 2021

Highlights for the long term period include a transition to a 
cooler and more active pattern late this week into next week, with
chances for rain on Saturday.

Thursday and Friday we see a slight lowering of temperatures each
day, with highs by Friday ranging from the mid 60s northwest to 
mid or upper 70s over the James River Valley. We enter into more 
of a broad southwest upper flow by Friday which will help bring 
increasing moisture and upper level forcing into the region, thus 
precipitation chances increase Thursday night through Saturday 
with a few chances of showers and possible thunderstorms during 
this timeframe. Uncertainty with strength and timing of impulses 
moving through the local area remain, but at this time the NBM is
pointing to Saturday as the timeframe with best precipitation
chances. With enough uncertainty remaining this far out, see no 
need for any changes to our given pops this far out.

Later in the weekend we lose the southwest upper flow as upper
level ridging builds temporarily over the region, ahead of another
upper level trough that digs over the western U.S. late in the
forecast period. 

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 717 PM CDT Tue Oct 5 2021

VFR conditions will prevail through the forecast period. Low-level
wind shear is expected tonight over south central North Dakota
into the James River Valley, affecting the KBIS and KJMS
terminals.


&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon CDT /11 AM MDT/ to 8 PM CDT /7 PM 
MDT/ Wednesday for NDZ001>003-009>011-017>021-031>034-040>045.

&&

$$

UPDATE...JJS
SHORT TERM...TWH
LONG TERM...TWH
AVIATION...JJS